Liquid crystal display device and electronic apparatus

ABSTRACT

Provided is a liquid crystal display device including: first and second substrates with a liquid crystal layer interposed therebetween; a first electrode formed on the liquid crystal layer side of the first substrate and having linear portions; a second electrode having linear portions formed along the linear portions of the first electrode and adjacent to the linear portions of the first electrode at a gap in plan view; and a third electrode formed on the liquid crystal layer side of the second substrate and having linear portions overlapping with the linear portions of the second electrode in plan view, wherein electric fields having different directions are generated between the first electrode and the second electrode and between the first electrode and the third electrode.

BACKGROUND

1. Technical Field

The present invention relates to a liquid crystal display device and anelectronic apparatus.

2. Related Art

As a liquid crystal display device, a vertical electric field modeliquid crystal display device such as a Twisted Nematic (TN) mode, aVertical Alignment (VA) mode or a Multi-domain Vertical Alignment (MVA)mode is widely used, but a lateral electric field mode liquid crystaldisplay device including electrodes on one substrate is also known. Inthe lateral electric field mode liquid crystal display device, theoperation principle of an In-Plane Switching (IPS) mode liquid crystaldisplay device will be described with reference to FIGS. 22 and 23 (forexample, see JP-A-2003-140188).

FIG. 22 is a schematic plan view of one pixel seen through a colorfilter substrate CF of a known IPS mode liquid crystal display device150. FIG. 23 is a cross-sectional view taken along line XXIII-XXIII ofFIG. 22.

This IPS mode liquid crystal display device 150 includes an arraysubstrate AR and a color filter substrate CF. In the array substrate AR,a plurality of scanning lines 154 and common lines 156 is provided inparallel on the surface of a first transparent substrate 152, and aplurality of signal lines 158 is provided in a direction crossing thescanning lines 154 and the common lines 156. On a central portion ofeach pixel, for example, a comb teeth-shaped counter electrode (alsoreferred to as a “common electrode”) 160 is provided from each of thecommon lines 156 in a band shape and a comb teeth-shaped pixel electrode162 is provided so as to be fitted into the counter electrode 160. Thesurfaces of the counter electrode 160 and the pixel electrode 162 are,for example, covered by a protective insulating film 164 formed ofsilicon nitride and an alignment film 166 formed of a polyimide or thelike.

In addition, a Thin Film Transistors (TFT) functioning as a switchingelement is formed at an intersection of each of the scanning lines 154and each of the signal lines 158. In this TFT, a semiconductor layer 168is disposed between each of the scanning lines 154 and each of thesignal lines 158, a portion of each of the signal lines on thesemiconductor layer 168 configures a source electrode S of the TFT, aportion of each of the scanning lines 154 under the semiconductor layer168 configures a gate electrode G, a conductive layer partiallyoverlapping with a portion of the semiconductor layer 168 configures adrain electrode D, and this drain electrode D is connected to the pixelelectrode 162.

In the color filter substrate CF, a color filter layer 172, an overcoatlayer 174 and an alignment film 176 are provided on the surface of asecond transparent substrate 170. The array substrate AR and the colorfilter substrate CF face each other such that the pixel electrode 162and the counter electrode 160 of the array substrate AR and the colorfilter layer 172 of the color filter substrate CF face each other.Subsequently, liquid crystal LC is filled between the array substrate ARand the color filter substrate CF, and polarization plates 178 and 180are arranged on the outsides of both substrates such that thepolarization directions thereof cross each other, thereby forming theIPS mode liquid crystal device 150.

As shown in FIG. 23, in the IPS mode liquid crystal display device 150,if an electric field is generated between the pixel electrode 162 andthe counter electrode 160, the liquid crystal aligned in a horizontaldirection turns in the horizontal direction such that the transmissionamount of light incident from a backlight can be controlled.

Next, the operation principle of a Fringe Field Switching (FFS) modeliquid crystal display device will be described with reference to FIGS.24 and 25 (for example, see 2001-56476).

FIG. 24 is a schematic plan view of one pixel seen through a colorfilter substrate CF of a known FFS mode liquid crystal display device190. FIG. 25 is a cross-sectional view taken along line XXV-XXV of FIG.24.

This FFS mode liquid crystal display device 190 includes an arraysubstrate AR and a color filter substrate CF. In the array substrate AR,a plurality of scanning lines 194 and common lines 196 is provided inparallel on the surface of a first transparent substrate 192, and aplurality of signal lines 198 is provided in a direction crossing thescanning lines 194 and the common lines 196. A counter electrode (alsoreferred to as a “common electrode”) 200 formed of a transparentmaterial, such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO), andconnected to each of the common lines 196 so as to cover a regionpartitioned by each of the scanning lines 194 and each of the signallines 198 is provided. A pixel electrode 206 formed of a transparentmaterial such as ITO and having a plurality of slits 204 formed thereinin a stripe shape is provided on the surface of the counter electrode200 with an insulating film 202 interposed therebetween. The surfaces ofthe pixel electrode 206 and the plurality of slits 204 are covered by analignment film 208.

A TFT functioning as a switching element is formed in the vicinity of anintersection of each of the scanning lines 194 and each of the signallines 198. In this TFT, a semiconductor layer 210 is disposed on thesurface of each of the scanning lines 194, a portion of each of thescanning lines 198 extends so as to cover a portion of the surface ofthe semiconductor layer 210 such that a source electrode S isconfigured, a portion of each of the scanning lines under thesemiconductor layer 210 configures a gate electrode G, a conductivelayer partially overlapping with a portion of the semiconductor layer210 configures a drain electrode D, and this drain electrode D isconnected to the pixel electrode 206.

In the color filter substrate CF, a color filter layer 214, an overcoatlayer 216 and an alignment film 218 are provided on the surface of asecond transparent substrate 212. The array substrate AR and the colorfilter substrate CF face each other such that the pixel electrode 206and the counter electrode 200 of the array substrate AR and the colorfilter layer 214 of the color filter substrate CF face each other.Subsequently, liquid crystal LC is filled between the array substrate ARand the color filter substrate CF, and polarization plates 220 and 222are arranged on the outsides of both substrates such that polarizationdirections thereof cross each other, thereby forming the FFS mode liquidcrystal device 190.

In the FFS mode liquid crystal display device 190, if an electric fieldis generated between the pixel electrode 206 and the counter electrode200, as shown in FIG. 25, this electric field is directed to the counterelectrode 200 at both sides of the pixel electrode 206. Accordingly, theliquid present on the pixel electrode 206 as well as the liquid crystalpresent in the slits 204 may move.

However, in the IPS mode liquid crystal display device 150, it isdifficult to twist liquid crystal molecules on the electrodes by thesize of the electric field strength such that brightness of displaydeteriorates. In the FFS mode liquid crystal display device 190, it isdifficult to twist liquid crystal molecules on the electrodes or betweenthe electrodes by the size of the electric field strength such thatbrightness of display deteriorates.

SUMMARY

The following aspects of the invention can be realized.

According to an aspect of the invention, there is provided a liquidcrystal display device including: first and second substrates with aliquid crystal layer interposed therebetween; a first electrode formedon the liquid crystal layer side of the first substrate and havinglinear portions; a second electrode having linear portions formed alongthe linear portions of the first electrode and adjacent to the linearportions of the first electrode at a gap in plan view; and a thirdelectrode formed on the liquid crystal layer side of the secondsubstrate and having linear portions overlapping with the linearportions of the second electrode in plan view, wherein electric fieldsof different directions are generated between the first electrode andthe second electrode and between the first electrode and the thirdelectrode.

The linear portions of the first electrode and the second electrode areformed adjacent to each other at a gap in plan view, and respectivelycorrespond to a pixel electrode and a counter electrode of an IPS modeliquid crystal display device. In addition, in the invention, the term“parallel” is not necessarily completely parallel if the electrodes donot cross each other, and includes a “<” shape, a zigzag shape and soon.

The linear portions of the second electrode and the linear portions ofthe third electrode are formed so as to overlap with each other in planview, and the electric field is generated between the first electrodeand the third electrode. Accordingly, in addition to the lateralelectric field between the linear portions of the first electrode andthe linear portions of the second electrode, the liquid crystalmolecules may move by the electric field between the linear portions ofthe first electrode and the linear portions of the third electrode, andthus a bright display can be realized without increasing a drivingvoltage. Accordingly, the liquid crystal display device capable ofenhancing (improving) the brightness or improving the driving voltage(low driving voltage) is provided.

In the liquid crystal display device, the third electrode may be formedof a transparent conductive material.

Since the third electrode is formed of the transparent conductivematerial, in particular, the light from the backlight is not shielded bythe third electrode and thus a liquid crystal display device capable ofrealizing a bright display is obtained. In addition, the first electrodeand the second electrode may be formed of a metallic material like theknown IPS mode liquid crystal display device, but is preferably formedof the transparent conductive material in view of luminance rise. Inaddition, a known material such as ITO or IZO may be used as thetransparent conductive material.

In the liquid crystal display device, a potential of the third electrodemay be at least one of a potential of the second electrode, anintermediate potential between the voltage of the first electrode andthe voltage of the second electrode, a fixed potential or a floatingstate in potential.

By setting the potential of the third electrode to a defined potential,it is possible to prevent the linear portions of the third electrodesfrom disturbing the alignment of the liquid crystal.

In the liquid crystal display device, the linear portions of the thirdelectrode may have a longitudinal direction along the scanning lines orsignal lines formed on the first substrate.

Since the third electrode can be efficiently formed in the vicinity ofthe switching element or the like, a numerical aperture can be enlargedwithout waste.

The liquid crystal display device may further include a fourth electrodehaving linear portions formed nearer the first substrate side than thefirst electrode and the second electrode with an insulating filminterposed therebetween, and a fifth electrode having linear portionsformed along the linear portions of the fourth electrode and adjacent tothe linear portions of the fourth electrode at a gap in plan view, thefirst electrode may be formed such that the linear portions thereofoverlap with those of one of the fourth electrode and the fifthelectrode in plan view, and the second electrode may be formed such thatthe linear portions thereof overlap with those of the other of thefourth electrode and the fifth electrode in plan view, and the firstelectrode may be electrically connected to the other of the fourthelectrode and the fifth electrode, and the second electrode may beelectrically connected to one of the fourth electrode and the fifthelectrode.

The first electrode is formed such that the linear portions thereofoverlap with those of one of the fourth electrode and the fifthelectrode in plan view, and the second electrode is formed such that thelinear portions thereof overlap with those of the other of the fourthelectrode and the fifth electrode in plan view. In addition, the fourthelectrode is electrically connected to the other of the first electrodeand the second electrode and the fifth electrode is electricallyconnected to one of the first electrode and the second electrode.Accordingly, two pairs of electrodes overlapping with each other in planview with the insulating film interposed therebetween have the samearrangement relationship as the FFS mode liquid crystal display deviceand the pairs of electrodes adjacent on the same plane have the samearrangement relationship as the IPS mode liquid crystal display device.

Capacitors are formed in the two pairs of electrodes overlapping witheach other in plan view with the insulating film interposedtherebetween, and the capacitors are connected in parallel. As a result,since the storage capacitor larger than that of the known FFS modeliquid crystal display device is formed, a liquid crystal display devicewith less flickers is obtained. In addition, since the driving of theliquid crystal in the FFS mode can be realized in all the electrodes, abright display can be realized, an intermediate configuration of the IPSmode and the FFS mode is obtained with respect to symmetry of theelectrodes, generation of a DC component is reduced, and a burn-inphenomenon is improved. The FFS mode liquid crystal display devicehaving the IPS mode property, in which the burn-in phenomenon or flickeris hard to occur, the numerical aperture is large and a bright displayis realized, and is obtained.

In the liquid crystal display device, the widths of the linear portionsof the fourth electrode and the linear portions of the fifth electrodemay be larger than those of the linear portions of the first electrodeand the linear portions of the second electrode, respectively.

Since the characteristics of the FFS mode liquid crystal display deviceappears strongly, a high applied voltage is necessary. However, sincegood fringe field effect is generated in all the electrodes, a liquidcrystal display device capable of realizing a brighter display isobtained. In addition, since allowance for pair shifting is increasedwhen the liquid crystal display device of this aspect is manufactured,the liquid crystal display device is easily manufactured.

In the liquid crystal display device, the widths of the linear portionsof the fourth electrode and the linear portions of the fifth electrodemay be equal to those of the linear portions of the first electrode andthe linear portions of the second electrode, respectively.

By this configuration, the allowance for misalignment of a mask uponmanufacture is decreased but the applied voltage may be low. Inaddition, since the fringe field is generated in all the electrodes, aliquid crystal display device capable of realizing a bright display isobtained.

According to another aspect of the invention, there is provided a liquidcrystal display device including a plurality of sub pixel regions, thedevice including: first and second substrates with a liquid crystallayer interposed therebetween; a first electrode formed on the liquidcrystal layer side of the first substrate; a second electrode formednearer the liquid crystal layer side than the first electrode with aninsulating film interposed therebetween and having a plurality of linearportions in a region overlapping with the first electrode in plan view,wherein a third electrode having a plurality of linear portions isformed on the liquid crystal layer side of the second substrate, thelinear portions of the third electrode do not overlap with the linearportions of the second electrode in plan view and have portions formedalong the linear portions of the second electrode, and electric fieldsare generated between the second electrode and the third electrode andbetween the second electrode and the first electrode.

The linear portions of the first electrode and the second electrode areformed with the insulating film interposed therebetween, and correspondto the pixel electrode and the counter electrode of the FFS mode liquidcrystal display device.

The linear portions of the second electrode and the linear portions ofthe third electrode are formed so as not to overlap with each other inplan view, and the electric field is generated between the secondelectrode and the third electrode. Accordingly, in addition to thelateral electric field between the first electrode and the secondelectrode, the liquid crystal molecules may move by the electric fieldbetween the linear portions of the second electrode and the linearportions of the third electrode, and thus a bright display can berealized without increasing the driving voltage. As a result, thetransmissivity can be improved without decreasing the space between thelinear portions of the second electrode on the first substrate side. Inaddition, the driving voltage can be decreased by the electrodeconfiguration (the width between the electrodes or the width of thecounter electrode) or the electrode location. Accordingly, the liquidcrystal display device capable of enhancing (improving) brightness orimproving the driving voltage (low driving voltage) is provided.

In the liquid crystal display device, the third electrode may be formedof a transparent conductive material.

Since the third electrode is formed of the transparent conductivematerial, in particular, the light from the backlight is not shielded bythe third electrode and thus a liquid crystal display device capable ofrealizing a bright display is obtained. In addition, the secondelectrode may be formed of a metal material like the known FFS modeliquid crystal display device, but is preferably formed of thetransparent conductive material in view of luminance rise. In addition,a known material such as ITO or IZO may be used as the transparentconductive material.

In the liquid crystal display device, a potential of the third electrodemay be at least one of a potential of the second electrode, anintermediate potential between the voltage of the first electrode andthe voltage of the second electrode, a fixed potential or a floatingstate in potential.

By setting the potential of the third electrode to a defined potential,it is possible to prevent the linear portions of the third electrodesfrom disturbing the alignment of the liquid crystal.

In the liquid crystal display device, the linear portions of the thirdelectrode may have a longitudinal direction along scanning lines orsignal lines formed on the first substrate.

Since the third electrode can be efficiently formed in the vicinity ofthe switching element or the like, a numerical aperture can be enlargedwithout waste.

In the liquid crystal display device, gaps between the linear portionsof the third electrode may be different in at least one of the sub pixelregions.

Since allowance for pair shifting when the first and second substratesare assembled is increased, it is possible to reduce deterioration oftransmissivity due to pair shifting.

According to another aspect of the invention, there is provided anelectronic apparatus including the above-described liquid crystaldisplay device in a display unit.

By including the liquid crystal display device in the display unit, itis possible to realize high-quality display in the display unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a circuit diagram of a plurality of sub pixel regions formedin a matrix configuring a liquid crystal display device according to afirst embodiment of the invention.

FIG. 2 is a plan view of any one sub pixel seen through a color filtersubstrate of the liquid crystal display device according to the firstembodiment of the invention.

FIG. 3 is a partial cross-sectional view taken along line III-III ofFIG. 2.

FIG. 4 is a partial cross-sectional view taken along line IV-IV of FIG.2.

FIG. 5 is a graph of T-V characteristics of the liquid crystal displaydevice according to the first embodiment of the invention and a knownIPS structure.

FIG. 6 is a plan view of any one sub pixel seen through a color filtersubstrate of a liquid crystal display device according to a secondembodiment of the invention.

FIG. 7 is a partial cross-sectional view taken along line VII-VII ofFIG. 6.

FIG. 8 is a partial cross-sectional view taken along line VIII-VIII ofFIG. 6.

FIG. 9 is a graph of T-V characteristics of the liquid crystal displaydevice according to the second embodiment of the invention and a knownFFS structure.

FIG. 10 is a plan view of any one sub pixel seen through a color filtersubstrate of a liquid crystal display device according to a thirdembodiment of the invention.

FIG. 11 is a plan view of any one sub pixel seen through a color filtersubstrate of a liquid crystal display device according to a fourthembodiment of the invention.

FIG. 12 is a partial cross-sectional view taken along line XII-XII ofFIG. 11.

FIG. 13 is a partial cross-sectional view taken along line XIII-XIII ofFIG. 11.

FIG. 14 is a plan view of any one sub pixel seen through a color filtersubstrate of a liquid crystal display device according to a fifthembodiment of the invention.

FIG. 15 is a partial cross-sectional view taken along line XV-XV of FIG.14.

FIG. 16 is a partial cross-sectional view taken along line XVI-XVI ofFIG. 14.

FIG. 17 is a graph of T-V characteristics of the liquid crystal displaydevice according to the fifth embodiment of the invention and a knownFFS structure.

FIG. 18 is a plan view of any one sub pixel seen through a color filtersubstrate of a liquid crystal display device according to a sixthembodiment of the invention.

FIG. 19 is a cross-sectional view of a liquid crystal display deviceaccording to a seventh embodiment of the invention.

FIG. 20 is a view explaining linear portions of a third electrodeaccording to the seventh embodiment of the invention.

FIG. 21 is a perspective view of a mobile telephone which is an exampleof an electronic apparatus in which the liquid crystal display deviceaccording to the present embodiment is mounted in a display unit.

FIG. 22 is a schematic plan view of one pixel seen through a colorfilter substrate of a known IPS mode liquid crystal display device.

FIG. 23 is a cross-sectional view taken along line

XXIII-XXIII of FIG. 22.

FIG. 24 is a schematic plan view of one pixel seen through a colorfilter substrate of a known FFS mode liquid crystal display device.

FIG. 25 is a cross-sectional view taken along line XXV-XXV of FIG. 24.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, liquid crystal display devices according to embodiments ofthe invention will be described with references to the accompanyingdrawings. In each view used for the embodiments, the scale of each layeror each member is differentiated from each other in order that eachlayer or each member has a size capable of being identified in the view.

First Embodiment

FIG. 1 is a circuit diagram of a plurality of sub pixel regions formedin a matrix configuring a liquid crystal display device 2 according tothe present embodiment.

In an image display region of the liquid crystal display device 2according to the present embodiment, a plurality of sub pixels regionsis arranged in a matrix. In each of the sub pixel regions, a firstelectrode 10 and a TFT 12 for controlling switching of the firstelectrode 10 are formed. Each of signal lines 16 extending from a signalline driving circuit 14 is electrically connected to a source of the TFT12. The signal line driving circuit 14 supplies image signals S1, S2, .. . , and Sn to pixels via the signal lines 16. The image signals S1 toSn may be line-sequentially supplied in this order or may be supplied toa group of a plurality of adjacent signal lines 16.

Each of scanning lines 20 extending from a scanning line driving circuit18 is electrically connected to a gate of the TFT 12. The scanning linedriving circuit supplies scanning signals G1, G2, . . . , and Gm to thescanning lines 20 at predetermined timings in a pulsed manner. Each ofthe scanning signals G1 to Gm are line-sequentially applied to the gateof the TFT 12 in this order. The first electrode 10 is electricallyconnected to a drain of the TFT 12. The TFT 12 functioning as theswitching element is turned on only during a predetermined period by theinput of each of the scanning signals G1, G2, . . . , and Gm such thateach of the image signals S1, S2, and Sn supplied from the signal lines16 is written in the first electrode 10 at a predetermined timing.

Each of the image signals S1, S2, . . . , and Sn having a predeterminedlevel and written in the liquid crystal via the first electrode 10 isheld by a liquid crystal capacitor formed between the first electrode 10and a common electrode during a predetermined period. In order toprevent the held image signal from being leaked, a storage capacitor 22is formed in parallel to the liquid crystal capacitor. The storagecapacitor 22 is interposed between the drain of the TFT 12 and acapacitive line 24.

Next, the planar and cross-sectional configurations of the liquidcrystal display device 2 will be described with reference to FIGS. 2 to4.

FIG. 2 is a plan view of any one sub pixel seen through a color filtersubstrate CF of the liquid crystal display device 2 according to thepresent embodiment. FIG. 3 is a partial cross-sectional view taken alongline III-III of FIG. 2, and FIG. 4 is a partial cross-sectional viewtaken along line IV-IV of FIG. 2.

In each of the sub pixel regions of the liquid crystal display device 2according to the present embodiment, the color filter layer 26 havingthe substantially same planar shape as the sub pixel region is provided.A columnar spacer 28 for separating the array substrate AR and the colorfilter substrate CF at a predetermined gap and constantly holding aliquid crystal layer thickness (cell gap) is erected on a right lowercorner of each of the sub pixel regions.

The liquid crystal display device 2 includes the array substrate (firstsubstrate) AR and the color filter substrate (second substrate) CF. Inthe array substrate AR, a plurality of scanning lines 20 and signallines 16 is formed in a matrix on the surface of a display region of afirst transparent substrate 30 such as a glass substrate so as to crosseach other in a state of being insulated from each other by a gateinsulating film 32, and a common line 34 is formed at a peripheral edgeportion of the display region. Each of regions surrounded by thescanning lines 20 and the signal lines 16 forms each pixel (alsoreferred to as a “sub pixel”). On the first transparent substrate 30,the TFT 12 is, for example, formed in each pixel as the switchingelement. In this TFT 12, a semiconductor layer 36 is disposed on thesurface of each of the scanning lines 20, a portion of each of thesignal lines 16 extends so as to cover a portion of the surface of thesemiconductor layer 36 such that a source electrode S is configured, aportion of each of the scanning lines under the semiconductor layer 36configures a gate electrode G, a conductive layer partially overlappingwith a portion of the semiconductor layer 36 configures a drainelectrode D, and this drain electrode D is connected to the firstelectrode 10. A passivation film 38 formed of, for example, a siliconnitride layer or a silicon oxide layer is coated over the entire surfaceof the first transparent substrate 30 including the TFT 12.

A planarization film 40 formed of an organic material is formed on thesurface of the passivation film 38, and an insulating film 42 formed ofa silicon nitride layer or a silicon oxide layer is formed on thesurface of the planarization film 40 over the entire surface of thefirst transparent substrate 30. A first contact hole 44 is formed in theinsulating film 42, the planarization film 40 and the passivation film38 at a location corresponding to the drain electrode D of the TFT 12.The first electrode 10 and a second electrode 48 respectively havinglinear portions 10 a and 48 a extending along the signal lines 16 areformed on the surface of the insulating film 42 with a first separationregion 46 interposed therebetween (so as to be adjacent to each other ata gap in plan view) in parallel in each pixel. The first electrode 10has a plurality of linear portions 10 a and has a longitudinal directionin a Y-axis direction (extending direction of the signal lines 16/thelines for supplying the signals). The second electrode 48 has aplurality of linear portions 48 a and has a longitudinal direction inthe Y-axis direction. The first electrode 10 and the second electrode 48are preferably formed of a transparent conductive material such as ITOor IZO, in order to enlarge a numerical aperture so as to realize abright display, but may be formed of a metal material such as aluminum.

The first electrode 10 is electrically connected to the drain electrodeD of the TFT 12 via the first contact hole 44, and the second electrode48 is electrically connected to the common line 34 via a second contacthole 50 formed in the insulating film 42. Accordingly, in the liquidcrystal display device 2, the first electrode 10 functions as a pixelelectrode and the second electrode 48 functions as a counter electrode.

Accordingly, a pair of the linear portions 10 a of the first electrode10 and the linear portions 48 a of the second electrode 48 which areadjacent to each other on the same plane has the arrangementrelationship of an IPS mode liquid crystal display device. Any one ofthe first electrode 10 and the second electrode 48 is arbitrarily set asthe pixel electrode. However, the pair of electrodes which are adjacentto each other on the same plane needs to be a pair of the pixelelectrode and the counter electrode.

A first alignment film 52 is formed over the entire display regionincluding the surfaces of the first electrode 10 and the secondelectrode 48.

In addition, in the color filter substrate CF, a light shielding film 56is formed on the surface of a second transparent substrate 54 such as aglass substrate so as to cover locations corresponding to the scanninglines 20, the signal lines 16, the first contact hole 44, the secondcontact hole 50 and the TFT 12 of the array substrate AR. A color filterlayer 26 having a predetermined color is formed on the surface of thesecond transparent substrate 54 surrounded by the light shielding film56. In addition, an overcoat layer 58 is formed so as to cover thesurfaces of the light shielding film 56 and the color filter layer 26.

A patterned third electrode 60 formed of an ITO film is formed on theovercoat layer 58 in each pixel. By this configuration, the thirdelectrode 60 formed on the surface of the overcoat layer 58, forexample, equalizes irregularities due to the presence of the colorfilter layer 26 or the like so as to become flat, and thus a cell gapbecomes uniform. Therefore, according to the liquid crystal displaydevice 2 of the present embodiment, a liquid crystal display devicehaving good display quality is obtained. The third electrode 60 has aplurality of linear portions 60 a and has a longitudinal direction inthe Y-axis direction. The linear portions 60 a of the third electrode 60are arranged so as to overlap with the linear portions 48 a of thesecond electrode 48 in plan view. The third electrode 60 has slitsformed herein so as to overlap with the linear portions 10 a of thefirst electrode 10 in plan view. By this configuration, since the thirdelectrode 60 can be efficiently formed even in the vicinity of the TFT12 or the like, the numerical aperture can be enlarged without waste.

As the potential of the third electrode 60, at least one of the samepotential as the second electrode 48, an intermediate potential of thefirst electrode 10 and the second electrode 48, a fixed potential, afloating state and so on is applied. By this configuration, by settingthe potential of the third electrode 60 to a defined potential, it ispossible to prevent the linear portions 60 a of the third electrode 60from disturbing the alignment of the liquid crystal LC. In addition, apotential having a pulse shape may be applied to the third electrode 60.By this configuration, it is possible to permit high-speed response.

A predetermined potential may be applied to such a third electrode 60,instead of the case where the third electrode is brought into a floatingstate in potential. When the predetermined potential is applied to thethird electrode 60, the third electrode 60 formed on the side of theliquid crystal LC of the color filter substrate CF and the lines (notshown) formed on the array substrate AR are electrically connected. Incontrast, when the third electrode 60 is brought into the floatingstate, the conduction between the substrates is omitted. The thirdelectrode 60 is preferably formed of a transparent conductive materialsuch as ITO or IZO in order to enlarge the numerical aperture so as torealize a bright display, but may be formed of a metal material such asaluminum.

A second alignment film 64 is formed on the surfaces of the overcoatlayer 58 and the third electrode 60.

The array substrate AR and the color filter substrate CF face each othersuch that the linear portions 48 a of the second electrode 48 of thearray substrate AR and the linear portions 60 a of the third electrode60 of the color filter substrate CF face each other, and the liquidcrystal LC is filled therebetween. As the material of the liquid crystalLC, any one of a liquid crystal material having negative dielectricconstant anisotropy or a liquid crystal material having positivedielectric constant anisotropy may be used, but the liquid crystalmaterial of negative dielectric constant anisotropy is preferably used.If the liquid crystal material with negative dielectric constantanisotropy is used, a viewing angle under application of a selectivevoltage (voltage on) widens and the display characteristics of thedisplay device are not damaged. In addition, by using the liquid crystalhaving negative dielectric constant anisotropy, the influence of avertical electric field due to pair shifting can be reduced and thusallowance for pair shifting can be improved. In addition, in the linearportions 60 a of the third electrode 60, in order to minimize theinfluence of pair shifting, an electrode for applying a potential bypair shifting may be selected. In addition, the gap between the linearportions 60 a of the third electrode 60 in one pixel may be arbitrarilyshifted such that the influence of pair shifting is minimized.

A first polarization plate 66 and a backlight device (not shown) aredisposed outside the array substrate AR, and a second polarization plate68 is disposed outside the color filter substrate CF, thereby completingthe liquid crystal display device 2. A retardation film may be disposedbetween the substrates AR and CF and the polarization plates 66 and 68,if necessary.

Next, the operation of the liquid crystal display device 2 will bedescribed.

In the liquid crystal display device 2, the first electrode 10 functionsas the pixel electrode, and the second electrode 48 and the thirdelectrode 60 function as the counter electrode. In addition, the linearportions 48 a of the second electrode 48 and the linear portions 60 a ofthe third electrode 60 overlap with each other in plan view with thefirst alignment film 52, the liquid crystal LC and the second alignmentfilm 64 interposed therebetween. Accordingly, when the liquid crystaldisplay device 2 is activated, as shown in FIG. 3, an electric field E1is applied between the linear portions 10 a of the first electrode 10and the linear portions 48 a of the second electrode 48, and an electricfield E2 is applied between the linear portions 10 a of the firstelectrode 10 and the linear portions 60 a of the third electrode 60.

The liquid crystal molecules may move by the electric field E2 appliedbetween the linear portions 10 a of the first electrode 10 and thelinear portions 60 a of the third electrode 60. In addition, theoperation by the electric field E1 applied between the linear portions10 a of the first electrode 10 and the linear portions 48 a of thesecond electrode 48 is equal to that of the known IPS mode liquidcrystal display device 150 shown in FIGS. 15 and 16. Accordingly, theliquid crystal display device 2 operates as the IPS mode liquid crystaldisplay device between the linear portions 10 a of the first electrode10 and the linear portions 48 a of the second electrode 48.

Comparison of Transmissivity-Driving Voltage Characteristics

FIG. 5 is a graph of transmissivity T-driving voltage V characteristicsof the liquid crystal display device 2 according to the presentembodiment and the known IPS mode liquid crystal display device. Inaddition, a graph L1 denotes the transmissivity T-driving voltage Vcharacteristics of the liquid crystal display device 2 and a graph L2denotes the transmissivity T-driving voltage V characteristics of theknown IPS mode liquid crystal display device.

When the graphs L1 and L2 of the transmissivity T-driving voltage Vcharacteristics are compared, the light transmissivity under applicationof the selective voltage Vs of the liquid crystal display device 2 ishigher than that of the known IPS mode liquid crystal display device.

According to the present embodiment, in addition to the lateral electricfield E1 between the linear portions 10 a of the first electrode 10 andthe linear portions 48 a of the second electrode 48, the liquid crystalmolecules may move by the electric field E2 between the linear portions10 a of the first electrode 10 and the linear portions 60 a of the thirdelectrode 60, and thus a bright display can be realized withoutincreasing the driving voltage. As a result, the transmissivity can beimproved without decreasing the first separation region 46 on the sideof the array substrate AR. Accordingly, the liquid crystal displaydevice 2 capable of enhancing (improving) brightness or improving thedriving voltage (low driving voltage) is provided.

Second Embodiment

Next, a liquid crystal display device 4 according to a second embodimentwill be described with reference to FIGS. 6 to 8.

FIG. 6 is a plan view of any one sub pixel seen through a color filtersubstrate CF of the liquid crystal display device 4 according to thepresent embodiment. FIG. 7 is a partial cross-sectional view taken alongline VII-VII of FIG. 6. FIG. 8 is a partial cross-sectional view takenalong line VIII-VIII of FIG. 6. In addition, in FIGS. 6 to 8, the samecomponents as the liquid crystal display device 2 of the firstembodiment shown in FIGS. 2 to 4 are denoted by the same referencenumerals and the detailed description thereof will be omitted.

The liquid crystal display device 4 according to the present embodimentis different from the liquid crystal display device 2 according to thefirst embodiment in that fourth and fifth electrodes 70 and 72 of lowerelectrodes are formed in addition to the first and second electrodes 10and 48 on the side of the array substrate AR with an insulating film 42interposed therebetween.

In the liquid crystal display device 4, the fourth electrode 70 and thefifth electrode 72 respectively having linear portions 70 a and 72 aextending along the signal lines 16 in parallel with a second separationregion 74 interposed therebetween in each pixel are formed on thesurface of the planarization film 40. The fourth electrode 70 has theplurality of linear portions 70 a and has a longitudinal direction inthe Y-axis direction. The fifth electrode 72 has the plurality of linearportions 72 a and has a longitudinal direction in the Y-axis direction.One of the pair of the fourth electrode 70 and the fifth electrode 72may be formed of a metal material such as aluminum, but at least one ofthe electrodes is preferably formed of a transparent conductive materialsuch as ITO or IZO, in order to increase the numerical aperture.

The fifth electrode 72 is electrically connected to the drain electrodeD of the TFT 12 via a first contact 44, and the fourth electrode 70 iselectrically connected to the common line 34. Accordingly, the fifthelectrode 72 functions as the pixel electrode and the fourth electrode70 functions as the counter electrode.

The insulating film 42 formed of a silicon nitride layer or a siliconoxide layer is formed on the entire surface of the first transparentsubstrate 30 on which the fourth electrode 70 and the fifth electrode 72are formed. The first electrode 10 and the second electrode 48respectively having the linear portions 10 a and 48 a extending alongthe signal lines 16 in parallel with the first separation region 46interposed therebetween in each pixel are formed on the surface of theinsulating film 42. The linear portions 10 a of the first electrode 10and the linear portions 48 a of the second electrode 48 are formed so asto overlap with the linear portions 72 a of the fifth electrode 72 andthe linear portions 70 a of the fourth electrode 70 in plan view.

The widths of the linear portions 70 a of the fourth electrode 70 andthe linear portions 72 a of the fifth electrode 72 is larger than thoseof the linear portions 10 a of the first electrode 10 and the linearportions 48 a of the second electrode 48. By this configuration, sinceallowance for misalignment of a mask when the first electrode 10 and thesecond electrode 48 are formed on the surface of the insulating film 42by a photolithography is increased, manufacture of the device isfacilitated. In addition, the widths of the linear portions 70 a of thefourth electrode 70 and the linear portions 72 a of the fifth electrode72 may be equal to those of the linear portions 10 a of the firstelectrode 10 and the linear portions 48 a of the second electrode 48. Bythis configuration, the allowance for misalignment of the mask uponmanufacture is decreased, but an applied voltage may be low and a fringefield is generated in all the electrodes. Thus, the liquid crystaldisplay device 4 with a bright display is obtained. In particular, themutual change of the widths of the linear portions 70 a of the fourthelectrode 70 and the linear portions 72 a of the fifth electrode 72 andthe mutual change of the widths of the linear portions 10 a of the firstelectrode 10 and the linear portions 48 a of the second electrode 48 donot have an advantage. Accordingly, the widths of the linear portions 70a of the fourth electrode 70 and the linear portions 72 a of the fifthelectrode 72 may be substantially equal to each other, and the widths ofthe linear portions 10 a of the first electrode 10 and the linearportions 48 a of the second electrode 48 may be substantially equal toeach other.

The fifth electrode 72 is electrically connected to the drain electrodeD of the TFT 12 via the first contact hole 44, and is electricallyconnected to the first electrode 10. In addition, the fourth electrode70 is electrically connected to the second electrode 48 via the secondcontact hole 50.

Accordingly, the pair formed of the linear portions 10 a of the firstelectrode 10 and the linear portions 70 a of the fourth electrode 70overlapping with each other in plain view and the pair formed of thelinear portions 48 a of the second electrode 48 and the linear portions72 a of the fifth electrode 72 have the same arrangement relationship asthe known FFS mode liquid crystal display device 190 shown in FIGS. 17and 18. In addition, the pair formed of the linear portions 10 a of thefirst electrode 10 and the linear portions 48 a of the second electrode48 adjacent to each other on the same plane and the pair formed of thelinear portions 70 a of the fourth electrode 70 and the linear portions72 a of the fifth electrode 72 have the same arrangement relationship asthe known IPS mode liquid crystal display device 150 shown in FIGS. 15and 16.

In addition, in the color filter substrate CF, the third electrode 60formed of an ITO film is formed on the light shielding film 56 and thecolor filter layer 26.

Next, the operation of the liquid crystal display device 4 will bedescribed.

In the liquid crystal display device 4, the first electrode 10 and thefifth electrode 72 function as the pixel electrode, and the secondelectrode 48, the fourth electrode 70 and the third electrode 60function as the counter electrode. In addition, the linear portions 10 aof the first electrode 10 and the linear portions 70 a of the fourthelectrode 70 overlap with each other in plan view with the insulatingfilm 42 interposed therebetween, the linear portions 48 a of the secondelectrode 48 and the linear portions 72 a of the fifth electrode 72overlap with each other in plan view with the insulating film 42interposed therebetween, and the linear portions 48 a of the secondelectrode 48 and the linear portions 60 a of the third electrode 60overlap with each other in plan view with the first alignment film 52,the liquid crystal LC and the second alignment film 64 interposedtherebetween. Accordingly, when the liquid crystal display device 4 isactivated, as shown in FIG. 7, an electric field E1 is applied betweenthe linear portions 10 a of the first electrode 10 and the linearportions 48 a of the second electrode 48, an electric field E2 isapplied between the linear portions 10 a of the first electrode 10 andthe linear portions 60 a of the third electrode 60, and an electricfield E3 is applied between the linear portions 10 a of the firstelectrode 10 and the linear portions 70 a of the fourth electrode 70. Inaddition, an electric field E4 is applied between the linear portions 72a of the fifth electrode 72 and the linear portions 48 a of the secondelectrode 48 in the reverse direction to the electric field E3.

The liquid crystal molecules may move by the electric field E2 appliedbetween the linear portions 10 a of the first electrode 10 and thelinear portions 60 a of the third electrode 60. In addition, theoperation by the electric field E1 applied between the linear portions10 a of the first electrode 10 and the linear portions 48 a of thesecond electrode 48 is equal to that of the known IPS mode liquidcrystal display device shown in FIGS. 15 and 16. Accordingly, the liquidcrystal display device 4 operates as the IPS mode liquid crystal displaydevice between the linear portions 10 a of the first electrode 10 andthe linear portions 48 a of the second electrode 48. In addition, theoperation by the electric field E3 applied between the linear portions10 a of the first electrode 10 and the linear portions 70 a of thefourth electrode 70 and the operation by the electric field E4 appliedbetween the linear portions 72 a of the fifth electrode 72 and thelinear portions 48 a of the second electrode 48 are equal to that of theknown FFS mode liquid crystal display device shown in FIGS. 17 and 18.Accordingly, the liquid crystal display device operates as the FFS modeliquid crystal display device between the linear portions 10 a of thefirst electrode 10 and the linear portions 70 a of the fourth electrode70 and between the linear portions 48 a of the second electrode 48 andthe linear portions 72 a of the fifth electrode 72.

Comparison of Transmissivity-Driving Voltage Characteristics

FIG. 9 is a graph of transmissivity T-driving voltage V characteristicsof the liquid crystal display device 4 according to the presentembodiment and the known FFS mode liquid crystal display device. Inaddition, a graph L3 denotes the transmissivity T-driving voltage Vcharacteristics of the liquid crystal display device 4 and a graph L4denotes the transmissivity T-driving voltage V characteristics of theknown FFS mode liquid crystal display device.

When the graphs L3 and L4 of the transmissivity T-driving voltage Vcharacteristics are compared, the light transmissivity under applicationof the selective voltage Vs of the liquid crystal display device 4 ishigher than that of the known FFS mode liquid crystal display device.

According to the present embodiment, the linear portions 10 a of thefirst electrode 10 overlap with the linear portions 70 a of the fourthelectrode 70 in plan view and the linear portions 48 a of the secondelectrode 48 overlap with the linear portions 72 a of the fifthelectrode 72 in plan view. In addition, the fourth electrode 70 iselectrically connected to the second electrode 48, and the fifthelectrode 72 is electrically connected to the first electrode 10.Accordingly, the two pairs of electrodes overlapping with each other inplain view with the insulating film 42 interposed therebetween have thesame arrangement relationship as the FFS mode liquid crystal displaydevice, and the pair of electrodes adjacent to each other on the sameplane has the same arrangement relationship as the IPS mode liquidcrystal display device.

Capacitors are formed in the two pairs of electrodes overlapping witheach other in plan view with the insulating film 42 interposedtherebetween and are connected in parallel. Accordingly, as a result,since a storage capacitor larger than that of the known FFS mode liquidcrystal display device is formed, the liquid crystal display device 4with less flickers is obtained. In addition, since the driving of theliquid crystal in the FFS mode can be realized in all the electrodes, abright display can be realized, an intermediate configuration of the IPSmode and the FFS mode is obtained with respect to symmetry of theelectrodes, generation of a DC component is reduced, and a burn-inphenomenon is improved. The FFS mode liquid crystal display device 4having the IPS mode property, in which the burn-in phenomenon or flickeris hard to occur, the numerical aperture is large and a bright displayis realized, is obtained.

Third Embodiment

Next, a liquid crystal display device 6 according to a third embodimentwill be described with reference to FIG. 10.

FIG. 10 is a plan view of any one sub pixel seen through a color filtersubstrate CF of the liquid crystal display device 6 according to thepresent embodiment. In FIG. 10, the same components as the liquidcrystal display device 4 of the second embodiment shown in FIG. 6 aredenoted by the same reference numerals and the detailed descriptionthereof will be omitted. The cross-sectional views of FIG. 10corresponding to line VII-VII and VIII-VIII of FIG. 6 are equal to FIGS.7 and 8 and thus showing and detailed description thereof will beomitted.

The liquid crystal display device 6 according to the present embodimentis different from the liquid crystal display device 4 according to thesecond embodiment in that, whereas the linear portions 10 a of the firstelectrode 10 and the linear portions 48 a of the second electrode 48straightly extend along the signal lines 16 in the liquid crystaldisplay device 4 according to the second embodiment, the center portionsof the linear portions 10 a of the first electrode 10, the linearportions 48 a of the second electrode 48, the linear portions 70 a ofthe fourth electrode 70 and the linear portions 72 a of the fifthelectrode 72 are bent in the liquid crystal display device 6 accordingto the present embodiment. The linear portions 60 a of the thirdelectrode 60 disposed so as to overlap with the linear portions 48 a ofthe second electrode 48 in plan view are also bent.

The liquid crystal display device 6 is a so-called dual-domain device inwhich the linear portions 10 a, 48 a, 60 a, 70 a and 72 a of the firstto fifth electrodes 10, 48, 60, 70 and 72 are bent using the centralportion of each pixel as a border. The rotation direction of the liquidcrystal molecules in an upper half region when viewed from a front sideof paper and the rotation direction of the liquid crystal molecules in alower half region when viewed from the front side of paper are oppositeto each other, using the central portion of the pixel as a border.

According to the present embodiment, by providing a dual-domainelectrode structure, color shift such as yellowish tone or bluish tonecan be suppressed by a viewing angle.

Fourth Embodiment

Next, a liquid crystal display device 8 according to a fourth embodimentwill be described with reference to FIGS. 11 to 13.

FIG. 11 is a plan view of any one sub pixel seen through the colorfilter substrate CF of the liquid crystal display device 8 according tothe present embodiment. FIG. 12 is a partial cross-sectional view takenalong line XII-XII of FIG. 11. FIG. 13 is a partial cross-sectional viewtaken along line XIII-XIII of FIG. 11. In addition, in FIGS. 11 to 13,the same components as the liquid crystal display device 6 of the thirdembodiment shown in FIGS. 10, 7 and 8 are denoted by the same referencenumerals and the detailed description thereof will be omitted.

The liquid crystal display device 8 according to the present embodimentis different from the liquid crystal display device 6 according to thethird embodiment in that a sixth electrode 78 for applying a potentialdifferent from that of the third electrode 60 is formed on the side ofthe color filter substrate CF in addition to the configuration of theliquid crystal display device 6 according to the third embodiment.

In the liquid crystal display device 8, the patterned sixth electrode 78formed of an ITO film is formed on the overcoat layer 58 in each pixel.The sixth electrode has a plurality of linear portions 78 a and has alongitudinal direction in the Y-axis direction. The linear portions 78 aof the sixth electrode 78 extend along the signal lines 16 in parallelwith the linear portions 60 a of the third electrode 60 and a thirdseparation region 80 interposed therebetween. The linear portions 78 aof the sixth electrode 78 are disposed so as to overlap with the linearportions 10 a of the first electrode 10 in plan view. The sixthelectrode 78 has slits formed therein so as to overlap with the linearportions 48 a of the second electrode 48 in plan view.

As the potential of the sixth electrode 78, at least one of the samepotential as the first electrode 10, an intermediate potential of thefirst electrode 10 and the second electrode 48, a fixed potential, afloating state and so on is applied. By this configuration, by settingthe potential of the sixth electrode 78 to a defined potential, it ispossible to prevent the linear portions 78 a of the sixth electrode 78from disturbing the alignment of the liquid crystal LC. In addition, apotential having a pulse shape may be applied to the sixth electrode 78.By this configuration, it is possible to permit high-speed response.

A predetermined potential may be applied to such a sixth electrode 78,instead of the case where the sixth electrode is brought into a floatingstate in potential. When the predetermined potential is applied to thesixth electrode 78, the sixth electrode 78 formed on the side of theliquid crystal LC of the color filter substrate CF and the lines (notshown) formed on the array substrate AR are electrically connected. Incontrast, when the sixth electrode 78 is brought into the floatingstate, the conduction between the substrates is omitted. The sixthelectrode 78 is preferably formed of a transparent conductive materialsuch as ITO or IZO in order to enlarge the numerical aperture so as torealize a bright display, but may be formed of a metal material such asaluminum. In the linear portions 78 a of the sixth electrode 78, inorder to minimize the influence of pair shifting, an electrode forapplying a potential by pair shifting may be selected. In addition, thegap between the linear portions 78 a of the sixth electrode 78 in onepixel may be arbitrarily shifted such that the influence of pairshifting is minimized.

A second alignment film 64 is formed on the surfaces of the overcoatlayer 58, the third electrode 60, and the sixth electrode 78.

The array substrate AR and the color filter substrate CF face each othersuch that the linear portions 10 a of the first electrode 10 and thelinear portions 48 a of the second electrode 48 of the array substrateAR and the linear portions 78 a of the sixth electrode 78 and the linearportions 60 a of the third electrode 60 of the color filter substrate CFrespectively face each other, and the liquid crystal LC is filledtherebetween.

Next, the operation of the liquid crystal display device 8 will bedescribed.

In the liquid crystal display device 8, the first electrode 10, thefifth electrode 72 and the sixth electrode 78 function as the pixelelectrode and the second electrode 48, the fourth electrode 70 and thethird electrode 60 function as the counter electrode. In addition, thelinear portions 10 a of the first electrode 10 and the linear portions70 a of the fourth electrode 70 overlap with each other in plan viewwith the insulating film 42 interposed therebetween, the linear portions48 a of the second electrode 48 and the linear portions 72 a of thefifth electrode 72 overlap with each other in plan view with theinsulating film 42 interposed therebetween, the linear portions 10 a ofthe first electrode 10 and the linear portions 78 a of the sixthelectrode 78 overlap with each other in plan view with the firstalignment film 52, the liquid crystal LC and the second alignment film64 interposed therebetween, and the linear portions 48 a of the secondelectrode 48 and the linear portions 60 a of the third electrode 60overlap with each other in plan view with the first alignment film 52,the liquid crystal LC and the second alignment film 64 interposedtherebetween. Accordingly, when the liquid crystal display device 8 isactivated, as shown in FIG. 12, an electric field E1 is applied betweenthe linear portions 10 a of the first electrode 10 and the linearportions 48 a of the second electrode 48, an electric field E2 isapplied between the linear portions 10 a of the first electrode 10 andthe linear portions 60 a of the third electrode 60, an electric field E3is applied between the linear portions 10 a of the first electrode 10and the linear portions 70 a of the fourth electrode 70, an electricfield E4 is applied between the linear portions 72 a of the fifthelectrode 72 and the linear portions 48 a of the second electrode 48 ina reverse direction to the electric field E3, and an electric field E5is applied between the linear portions 60 a of the third electrode 60and the linear portions 78 a of the sixth electrode 78. In addition, anelectric field E6 is applied between the linear portions 78 a of thesixth electrode 78 and the linear portions 48 a of the second electrode48 in the reverse direction to the electric field E2.

The liquid crystal molecules may move by the electric field E2 appliedbetween the linear portions 10 a of the first electrode 10 and thelinear portions 60 a of the third electrode 60. In addition, the liquidcrystal molecules may move by the electric field E6 applied between thelinear portions 78 a of the sixth electrode 78 and the linear portions48 a of the second electrode 48. In addition, the operation by theelectric field E1 applied between the linear portions 10 a of the firstelectrode 10 and the linear portions 48 a of the second electrode 48 andthe operation by the electric field E5 applied between the linearportions 78 a of the sixth electrode 78 and the linear portions 60 a ofthe third electrode 60 are equal to that of the known IPS mode liquidcrystal display device shown in FIGS. 15 and 16. Accordingly, the liquidcrystal display device 8 operates as the IPS mode liquid crystal displaydevice between the linear portions 10 a of the first electrode 10 andthe linear portions 48 a of the second electrode 48 and between thelinear portion 78 a of the sixth electrode 78 and the linear portions 60a of the third electrode 60. In addition, the operation by the electricfield E3 applied between the linear portions 10 a of the first electrode10 and the linear portions 70 a of the fourth electrode 70 and theoperation by the electric field E4 applied between the linear portions72 a of the fifth electrode 72 and the linear portions 48 a of thesecond electrode 48 are equal to that of the known FFS mode liquidcrystal display device shown in FIGS. 17 and 18. Accordingly, the liquidcrystal display device operates as the FFS mode liquid crystal displaydevice between the linear portions 10 a of the first electrode 10 andthe linear portions 70 a of the fourth electrode 70 and between thelinear portions 48 a of the second electrode 48 and the linear portions72 a of the fifth electrode 72.

According to the present embodiment, the liquid crystal molecules maymove by the electric field E5 between the linear portions 60 a of thethird electrode 60 and the linear portions 78 a of the sixth electrode78 on the side of the color filter substrate CF and the electric fieldE6 between the linear portions 78 a of the sixth electrode 78 and thelinear portions 48 a of the second electrode 48. Accordingly, a brightdisplay can be realized without increasing the driving voltage.

Fifth Embodiment

Next, the planar and cross-sectional configurations of the liquidcrystal display device 2 will be described with reference to FIGS. 14 to16.

FIG. 14 is a plan view of any one sub pixel seen through the colorfilter substrate CF of the liquid crystal display device 2 according tothe fifth embodiment. FIG. 15 is a partial cross-sectional view takenalong line XV-XV of FIG. 14. FIG. 16 is a partial cross-sectional viewtaken along line XVI-XVI of FIG. 14.

In each of the sub pixel regions of the liquid crystal display device 2according to the fifth embodiment, the color filter layer 26 having thesubstantially same planar shape as the sub pixel region is provided. Inaddition, the columnar spacer 28 for separating the array substrate ARand the color filter substrate CF at a predetermined gap and constantlyholding a liquid crystal layer thickness (cell gap) is erected on aright lower corner of each of the sub pixel regions.

The liquid crystal display device 2 includes the array substrate (firstsubstrate) AR and the color filter substrate (second substrate) CF. Inthe array substrate AR, the plurality of scanning lines 20 and signallines 16 is formed in a matrix on the surface of the display region ofthe first transparent substrate 30 such as a glass substrate so as tocross each other in a state of being insulated from each other by thegate insulating film 32, and the common line 34 is formed at aperipheral edge portion of the display region. Each of regionssurrounded by the scanning lines 20 and the signal lines 16 forms eachpixel (also referred to as a “sub pixel”). On the first transparentsubstrate 30, the TFT 12 is, for example, formed in each pixel as theswitching element. In this TFT 12, the semiconductor layer 36 isdisposed on the surface of each of the scanning lines 20, a portion ofeach of the signal lines 16 extends so as to cover a portion of thesurface of the semiconductor layer 36 such that a source electrode S isconfigured, a portion of each of the scanning lines under thesemiconductor layer 36 configures a gate electrode G, a conductive layerpartially overlapping with a portion of the semiconductor layer 36configures a drain electrode D, and this drain electrode D is connectedto the first electrode 10. The passivation film 38 formed of, forexample, a silicon nitride layer or a silicon oxide layer is coated overthe entire surface of the first transparent substrate 30 including theTFT 12.

The planarization film 40 formed of an organic material is formed on thesurface of the passivation film 38, and the first electrode 10 is formedon the surface of the planarization film 40. The first electrode 10 hasa rectangular shape in plan view and has a longitudinal direction in theY-axis direction (extending direction of the signal lines 16/the linesfor supplying the signals). The insulating film 42 formed of a siliconnitride layer or a silicon oxide layer is formed on the surface of thefirst electrode 10 and the planarization film 40 over the entire surfaceof the first transparent substrate 30. The first contact hole 44 isformed in the insulating film 42, the planarization film 40 and thepassivation film 38 at a location corresponding to the drain electrode Dof the TFT 12. The second electrode 48 having the linear portions 48 aextending along the signal lines 16 in each pixel is formed on thesurface of the insulating film 42. The second electrode 48 has theplurality of linear portions 48 a and has a longitudinal direction inthe Y-axis direction. The first electrode 10 and the second electrode 48are preferably formed of a transparent conductive material such as ITOor IZO, in order to enlarge the numerical aperture so as to realize abright display, but may be formed of a metal material such as aluminum.

The first electrode 10 is electrically connected to the drain electrodeD of the TFT 12 via the first contact hole 44, and the second electrode48 is electrically connected to the common line 34 via the secondcontact hole 50 formed in the insulating film 42. Accordingly, in theliquid crystal display device 2, the first electrode 10 functions as thecounter electrode and the second electrode 48 functions as the pixelelectrode.

Accordingly, a pair of the first electrode 10 and the linear portions 48a of the second electrode 48 which overlap with each other with theinsulating film 42 interposed therebetween is in the arrangementrelationship of an FFS mode liquid crystal display device. Any one ofthe first electrode 10 and the second electrode 48 is arbitrarily set asthe pixel electrode. However, the pair of electrodes which overlap witheach other with the insulating film 42 interposed therebetween needs tobe a pair of the pixel electrode and the counter electrode.

The first alignment film 52 is formed over the entire display regionincluding the surface of the second electrode 48.

In addition, in the color filter substrate CF, a light shielding film 56is formed on the surface of the second transparent substrate 54 such asa glass substrate so as to cover locations corresponding to the scanninglines 20, the signal lines 16, the first contact hole 44, the secondcontact hole 50 and the TFT 12 of the array substrate AR. The colorfilter layer 26 having a predetermined color is formed on the surface ofthe second transparent substrate 54 surrounded by the light shieldingfilm 56. In addition, the overcoat layer 58 is formed so as to cover thesurfaces of the light shielding film 56 and the color filter layer 26.

The patterned third electrode 60 formed of an ITO film is formed on theovercoat layer 58 in each pixel. By this configuration, the thirdelectrode 60 formed on the surface of the overcoat layer 58, forexample, equalizes irregularities due to the presence of the colorfilter layer 26 or the like so as to become flat, and thus a cell gapbecomes uniform. Therefore, according to the liquid crystal displaydevice 2 of the present embodiment, a liquid crystal display devicehaving good display quality is obtained. The third electrode 60 has aplurality of linear portions 60 a and has a longitudinal direction inthe Y-axis direction. The linear portions 60 a of the third electrode 60are arranged so as not to overlap with the linear portions 48 a of thesecond electrode 48 in plan view.

The linear portions 60 a of the third electrode 60 are located betweenthe linear portions 48 a of the second electrode 48 in plan view. Thethird electrode 60 has slits formed therein so as to overlap with thelinear portions 48 a of the second electrode 48 in plan view. By thisconfiguration, since the third electrode 60 can be efficiently formedeven in the vicinity of the TFT 12 or the like, the numerical aperturecan be enlarged without waste. The third electrode 60 is formed so as totraverse the plurality of sub pixel regions.

As the potential of the third electrode 60, at least one of the samepotential as the first electrode 10, an intermediate potential of thefirst electrode 10 and the second electrode 48, a fixed potential, afloating state and so on is applied. By this configuration, by settingthe potential of the third electrode 60 to a defined potential, it ispossible to prevent the linear portions 60 a of the third electrode 60from disturbing the alignment of the liquid crystal LC. In addition, apotential having a pulse shape may be applied to the third electrode 60.By this configuration, it is possible to permit high-speed response.

A predetermined potential may be applied to such a third electrode 60,instead of the case where the third electrode is brought into a floatingstate in potential. When the predetermined potential is applied to thethird electrode 60, the third electrode 60 formed on the side of theliquid crystal LC of the color filter substrate CF and the lines (notshown) formed on the array substrate AR are electrically connected. Incontrast, when the third electrode 60 is brought into the floatingstate, the conduction between the substrates is omitted. The thirdelectrode 60 is preferably formed of a transparent conductive materialsuch as ITO or IZO in order to enlarge the numerical aperture so as torealize a bright display, but may be formed of a metal material such asaluminum.

The second alignment film 64 is formed on the surfaces of the overcoatlayer 58 and the third electrode 60.

The array substrate AR and the color filter substrate CF face each othersuch that the linear portions 48 a of the second electrode 48 of thearray substrate AR and the linear portions 60 a of the third electrode60 of the color filter substrate CF do not overlap with each other, andthe liquid crystal LC is filled therebetween. As the material of theliquid crystal LC, any one of a liquid crystal material having negativedielectric constant anisotropy or a liquid crystal material havingpositive dielectric constant anisotropy may be used, but the liquidcrystal material having negative dielectric constant anisotropy ispreferably used. If the liquid crystal material having negativedielectric constant anisotropy is used, a viewing angle underapplication of a selective voltage (voltage on) widens and the displaycharacteristics of the display device are not damaged. In addition, byusing the liquid crystal having negative dielectric constant anisotropy,the influence of a vertical electric field due to pair shifting can bereduced and thus allowance for pair shifting can be improved.

The first polarization plate 66 and the backlight device (not shown) aredisposed outside the array substrate AR, and the second polarizationplate 68 is disposed outside the color filter substrate CF, therebycompleting the liquid crystal display device 2. A retardation film maybe disposed between the substrates AR and CF and the polarization plates66 and 68, if necessary.

Next, the operation of the liquid crystal display device 2 will bedescribed.

In the liquid crystal display device 2, the first electrode 10 and thethird electrode 60 function as the counter electrode, and the secondelectrode 48 functions as the pixel electrode. In addition, the linearportions 48 a of the second electrode 48 and the linear portions 60 a ofthe third electrode 60 do not overlap with each other in plan view withthe first alignment film 52, the liquid crystal LC and the secondalignment film 64 interposed therebetween. Accordingly, when the liquidcrystal display device 2 is activated, as shown in FIG. 15, an electricfield E1 is applied between the first electrode 10 and the linearportions 48 a of the second electrode 48, and an electric field E2 isapplied between the linear portions 48 a of the second electrode 48 andthe linear portions 60 a of the third electrode 60.

The liquid crystal molecules may move by the electric field E2 appliedbetween the linear portions 48 a of the second electrode 48 and thelinear portions 60 a of the third electrode 60. In addition, theoperation by the electric field E1 applied between the first electrode10 and the linear portions 48 a of the second electrode 48 is equal tothat of the known FFS mode liquid crystal display device 190 shown inFIGS. 17 and 18. Accordingly, the liquid crystal display device 2operates as the FFS mode liquid crystal display device between the firstelectrode 10 and the linear portions 48 a of the second electrode 48.

Comparison of Transmissivity-Driving Voltage Characteristics

FIG. 17 is a graph of transmissivity T-driving voltage V characteristicsof the liquid crystal display device 2 according to the fifth embodimentand the known FFS mode liquid crystal display device. In addition, agraph L1 denotes the transmissivity T-driving voltage V characteristicsof the liquid crystal display device 2 and a graph L2 denotes thetransmissivity T-driving voltage V characteristics of the known FFS modeliquid crystal display device.

When the graphs L1 and L2 of the transmissivity T-driving voltage Vcharacteristics are compared, the light transmissivity under applicationof the selective voltage Vs of the liquid crystal display device 2 ishigher than that of the known FFS mode liquid crystal display device.

According to the fifth embodiment, in addition to the lateral electricfield E1 between the first electrode 10 and the linear portions 48 a ofthe second electrode 48, the liquid crystal molecules may move by theelectric field E2 between the linear portions 48 a of the secondelectrode 48 and the linear portions 60 a of the third electrode 60, andthus a bright display can be realized without increasing the drivingvoltage. As a result, the transmissivity can be improved withoutdecreasing the space between the linear portions 48 a of the secondelectrode 48 on the side of the array substrate AR. In addition, thedriving voltage can be decreased by the electrode configuration (thewidth between the electrodes or the width of the counter electrode) orthe electrode location. Accordingly, the liquid crystal display device 2capable of enhancing (improving) brightness or improving the drivingvoltage (low driving voltage) is provided.

Sixth Embodiment

Next, a liquid crystal display device 4 according to a sixth embodimentwill be described with reference to FIG. 18.

FIG. 18 is a plan view of any one sub pixel seen through a color filtersubstrate CF of the liquid crystal display device 4 according to thesixth embodiment. In addition, in FIG. 18, the same components as theliquid crystal display device 2 of the fifth embodiment shown in FIG. 14are denoted by the same reference numerals and the detailed descriptionthereof will be omitted. In FIG. 18, the cross-sectional views of theportions corresponding to the lines XV-XV and XVI-XVI of FIG. 14 areequal to FIGS. 15 and 16 and thus showing and detailed descriptionthereof will be omitted.

The liquid crystal display device 4 according to the sixth embodiment isdifferent from the liquid crystal display device 2 according to thefifth embodiment in that, whereas the linear portions 48 a of the secondelectrode 48 straightly extends along the signal lines 16 in the liquidcrystal display device 2 according to the fifth embodiment, the centerportions of the linear portions 48 a of the second electrode 48 are bentin the liquid crystal display device 4 according to the sixthembodiment. The linear portions 60 a of the third electrode 60 disposedso as not to overlap with the linear portions 48 a of the secondelectrode 48 in plan view are also bent.

The liquid crystal display device 4 is a so-called dual-domain device inwhich the linear portions 48 a of the second electrode 48 and the linearportions 60 a of the third electrode 60 are bent using the centralportion of each pixel as a border. The rotation direction of the liquidcrystal molecules in an upper half region when viewed from a front sideof paper and the rotation direction of the liquid crystal molecules in alower half region when viewed from the front side of paper are oppositeto each other, using the central portion of the pixel as a border.

According to the sixth embodiment, by providing a dual-domain electrodestructure, color shift such as yellowish tone or bluish tone can besuppressed by a viewing angle.

Seventh Embodiment

Next, a liquid crystal display device 6 according to a seventhembodiment will be described with reference to FIGS. 19 and 20.

FIG. 19 is a cross-sectional view of the liquid crystal display device 6according to the seventh embodiment. FIG. 20 is a view explaining thelinear portions 60 a of the third electrode 60 according to the seventhembodiment. In addition, in FIG. 19, the same components as the liquidcrystal display device 2 of the fifth embodiment shown in FIG. 15 aredenoted by the same reference numerals and the detailed descriptionthereof will be omitted.

The liquid crystal display device 6 according to the seventh embodimentis different from the liquid crystal display device 2 according to thefifth embodiment in that, whereas the linear portions 60 a of the thirdelectrode 60 does not overlap with the linear portions 48 a of thesecond electrode 48 in plan view in the liquid crystal display device 2according to the fifth embodiment, the gaps between the linear portions60 a of the third electrode 60 are different in one pixel in the liquidcrystal display device 6 according to the present embodiment.

In the liquid crystal display device 6, the gaps between the linearportions 60 a of the third electrode 60 are different in at least onepixel. The gaps between the linear portions 60 a of the third electrode60 may be arbitrarily shifted in one pixel. For example, as shown inFIG. 19, the relationship between the gap S1 and the gap S2 between thelinear portions 60 a of the third electrode 60 is expressed as the gapS1>the gap S2. In detail, as shown in FIG. 20, compared with theimaginary linear portions 60 b disposed at the same gap S3, the linearportions 60 a located at the left side of the central linear portion 60a when viewed from the front side of paper has a relationship of the galS1>the gap S3, and the linear portion 60 a located at the right side hasa relationship of the gap S2>the gap S3.

According to the seventh embodiment, since allowance for pair shiftingwhen the array substrate AR and the color filter substrate CF areassembled is increased, it is possible to reduce the deterioration oftransmissivity due to pair shifting. In addition, in the linear portions60 a of the third electrode 60, in order to minimize the influence ofthe pair shifting, an electrode for applying a potential by pairshifting may be selected.

Electronic Apparatus

Next, an electronic apparatus including the above-described liquidcrystal display device will be described.

FIG. 21 is a perspective view of a mobile telephone 100 which is anexample of an electronic apparatus in which the liquid crystal displaydevice according to the present embodiment is mounted in a display unit.

The mobile telephone 100 according to the present embodiment includesthe liquid crystal display device according to each of theabove-described embodiments as a small-sized display unit 102, andincludes a plurality of operation buttons 104, an ear piece 106 and amouthpiece 108. Since the mobile telephone 100 includes the liquidcrystal display device according to each of the above-describedembodiments, an electronic apparatus with excellent display quality canbe provided.

The liquid crystal display device according to each of theabove-described embodiments may be suitably used as an image displayunit of an electronic book, a personal computer, a digital still camera,a liquid crystal TV set, a viewfinder-type or direct-view monitor typevideo tape recorder, a car navigation system, a pager, an electronicorganizer, an electronic calculator, a word processor, a workstation, avideophone, a POS terminal, or a touch-panel-equipped device, inaddition to the mobile telephone. The above-described electronicapparatus can be implemented as a display unit of such exemplaryelectronic devices. Even in any electronic apparatus, an electronicapparatus with excellent display quality can be provided.

Although the embodiments are described, for example, the followingmodified examples may be considered.

Modified Example 1

Although the linear portions 60 a of the third electrode 60 (the linearportions 78 a of the sixth electrode 78) have the longitudinal directionalong the signal lines 16 in the liquid crystal display device accordingto each of the above-described embodiments, the same effects areobtained even when the linear portions have the longitudinal directionalong the scanning lines 20.

Modified Example 2

Although a shield electrode generally used on the color filter substrateside is not included in the liquid crystal display device according toeach of the above-described embodiment, the color filter substrate mayhave the shield electrode. For example, since a conductor is notincluded on the color filter substrate side of a general lateralelectric field type liquid crystal display device, the shield electrodeneeds to be provided for an antistatic countermeasure. However, sincethe electrode is provided on the side of the liquid crystal LC of thecolor filter substrate CF in the present embodiment, the shieldelectrode is unnecessary. Even when the shield electrode for preventingelectrification due to static electricity in the color filter substrateCF is not formed, since the patterned linear portions 60 a of the thirdelectrode 60 are formed, the electrification due to static electricityis hard to occur in the color filter substrate CF, and the alignment ofthe liquid crystal is not disturbed even when electricity occurs. Inaddition, since the patterned linear portions 60 a of the thirdelectrode 60 are formed on the side of the liquid crystal LC of thecolor filter substrate CF, the electrodes patterned in the substratestate before the liquid crystal panel is assembled can be formed.

Modified Example 3

Although the liquid crystal display device according to each of theabove-described embodiments is a transmissive type liquid crystaldisplay device, the invention is not limited thereto. For example, areflective type or transflective and reflective type liquid crystaldisplay device may be used.

The entire disclosure of Japanese Patent application Nos: 2008-264870,field Oct. 14, 2008 and 2008-264870, field Oct. 14, 2008 are expresslyincorporated by reference herein.

1. A liquid crystal display device comprising: first and secondsubstrates with a liquid crystal layer interposed therebetween; a firstelectrode formed on the liquid crystal layer side of the first substrateand having linear portions; a second electrode having linear portionsformed along the linear portions of the first electrode and adjacent tothe linear portions of the first electrode at a gap in plan view; and athird electrode formed on the liquid crystal layer side of the secondsubstrate and having linear portions overlapping with the linearportions of the second electrode in plan view, wherein electric fieldshaving different directions are generated between the first electrodeand the second electrode and between the first electrode and the thirdelectrode.
 2. The liquid crystal display device according to claim 1,wherein the third electrode is formed of a transparent conductivematerial.
 3. The liquid crystal display device according to claim 1,wherein a potential of the third electrode is at least one of apotential of the second electrode, an intermediate potential between thevoltage of the first electrode and the voltage of the second electrode,a fixed potential or a floating state in potential.
 4. The liquidcrystal display device according to claim 1, wherein the linear portionsof the third electrode have a longitudinal direction along scanninglines or signal lines formed on the first substrate.
 5. The liquidcrystal display device according to claim 1, further comprising: afourth electrode having linear portions formed nearer the firstsubstrate side than the first electrode and the second electrode with aninsulating film interposed therebetween; and a fifth electrode havinglinear portions formed along the linear portions of the fourth electrodeand adjacent to the linear portions of the fourth electrode at a gap inplan view, wherein the first electrode is formed such that the linearportions thereof overlap with those of one of the fourth electrode andthe fifth electrode in plan view, and the second electrode is formedsuch that the linear portions thereof overlap with those of the other ofthe fourth electrode and the fifth electrode in plan view, and whereinthe first electrode is electrically connected to the other of the fourthelectrode and the fifth electrode, and the second electrode iselectrically connected to one of the fourth electrode and the fifthelectrode.
 6. The liquid crystal display device according to claim 5,wherein the widths of the linear portions of the fourth electrode andthe linear portions of the fifth electrode are larger than those of thelinear portions of the first electrode and the linear portions of thesecond electrode, respectively.
 7. The liquid crystal display deviceaccording to claim 5, wherein the widths of the linear portions of thefourth electrode and the linear portions of the fifth electrode areequal to those of the linear portions of the first electrode and thelinear portions of the second electrode, respectively.
 8. A liquidcrystal display device including a plurality of sub pixel regions, thedevice comprising: first and second substrates with a liquid crystallayer interposed therebetween; a first electrode formed on the liquidcrystal layer side of the first substrate; a second electrode formednearer the liquid crystal layer side than the first electrode with aninsulating film interposed therebetween and having a plurality of linearportions in a region overlapping with the first electrode in plan view,wherein a third electrode having a plurality of linear portions isformed on the liquid crystal layer side of the second substrate, thelinear portions of the third electrode do not overlap with the linearportions of the second electrode in plan view and have portions formedalong the linear portions of the second electrode, and electric fieldsare generated between the second electrode and the third electrode andbetween the second electrode and the first electrode.
 9. The liquidcrystal display device according to claim 8, wherein the third electrodeis formed of a transparent conductive material.
 10. The liquid crystaldisplay device according to claim 8, wherein a potential of the thirdelectrode may be at least one of a potential of the second electrode, anintermediate potential between the voltage of the first electrode andthe voltage of the second electrode, a fixed potential or a floatingstate in potential.
 11. The liquid crystal display device according toclaim 8, wherein the linear portions of the third electrode have alongitudinal direction along scanning lines or signal lines formed onthe first substrate.
 12. The liquid crystal display device according toclaim 8, wherein gaps between the linear portions of the third electrodeare different in at least one of the sub pixel regions.
 13. Anelectronic apparatus comprising the liquid crystal display deviceaccording to claim 1 in a display unit.